1. Field of the Invention
The present invention relates to a liquid sealant composition for application to materials such as concrete which rely upon hydration reactions for curing in order to prevent loss of water during the curing process. This allows the material to develop maximum strength and wear resistance during curing. The present invention also relates to a method of applying a liquid coating composition to a material such as concrete which relies upon hydration for curing in order to reduce or prevent water loss therefrom.
2. Description of the Prior Art
Wax emulsions made with fatty acids are known for use as sealants for the purpose of sealing against liquid water. However, such wax emulsions do not prevent passage of water vapor and therefore do not adequately seal in the moisture of hydration of concrete. An example of such a compound is Mastercure.RTM. W which has been taken off the market since it is relatively ineffective in preventing loss of water vapor from concrete during curing.
Several products exist which meet the ASTM specification C 309-95 for liquid membrane-forming compounds for curing concrete. Typical products used for this purpose are primary epoxy compounds and urethanes. However, these compositions suffer from the problem that they contain hazardous components such as volatile organic compounds.
Although polyvinyl alcohol is known as both a film-forming agent and an emulsifier, it does not meet ASTM standard C 309-95 when tested as a liquid membrane-forming compound for curing concrete. The reason for this is that although polyvinyl alcohol typically exhibits a low permeability to gases, it does not exhibit a low permeability to either ammonia or water vapor. As a result, polyvinyl alcohol is insufficient to prevent significant loss of water from concrete during curing.
Paraffinic compounds are known to be water repellant and thus paraffin is typically used as a component of wood preservative agents. For example, U.S. Pat. No. 4,389,446 discloses a composition useful as a wood preservative agent which includes an organic solvent, solid paraffin as a water repellant agent and a biocide.
U.S. Pat. No. 4,539,047 relates to clear coatings for preventing wood from discoloring as a result of exposure to ultraviolet rays. A coating composition which includes an unsaturated oil-containing resin dissolved in a solvent medium containing at least 50% of mineral spirits which has dispersed therein from about 13 to about 63 parts of granulated paraffin wax and from 0.5-20 parts of transparent ultraviolet-absorbing pigment per 100 parts of the resin, is disclosed for this purpose.
However, paraffin based coatings are not typically employed as liquid membrane-forming compounds for curing concrete since they suffer from a number of disadvantages. In particular, paraffin wax would be difficult to remove once the concrete is completely cured. Further, paraffin wax would be difficult to apply since it must be heated to melting prior to application. Further, paraffin wax does not form a strong film and it can be very messy particularly if it is employed in warm climates.
Accordingly, there remains a need in the art for a coating composition which can be used as a coating compound for the curing of concrete and other materials which rely on a hydration reaction for hardening.
There is also a need in the art for coating compounds for the curing of concrete and other similar materials which does not contain hazardous materials and/or volatile organic compounds.
These and other objects of the present invention will be apparent from the summary and detailed descriptions which follow.